全文获取类型
收费全文 | 649篇 |
免费 | 23篇 |
国内免费 | 1篇 |
专业分类
化学 | 531篇 |
晶体学 | 10篇 |
力学 | 5篇 |
数学 | 28篇 |
物理学 | 99篇 |
出版年
2022年 | 3篇 |
2021年 | 4篇 |
2020年 | 10篇 |
2019年 | 11篇 |
2018年 | 8篇 |
2017年 | 2篇 |
2016年 | 12篇 |
2015年 | 15篇 |
2014年 | 12篇 |
2013年 | 31篇 |
2012年 | 30篇 |
2011年 | 40篇 |
2010年 | 19篇 |
2009年 | 22篇 |
2008年 | 36篇 |
2007年 | 36篇 |
2006年 | 41篇 |
2005年 | 44篇 |
2004年 | 41篇 |
2003年 | 29篇 |
2002年 | 16篇 |
2001年 | 25篇 |
2000年 | 8篇 |
1999年 | 8篇 |
1998年 | 5篇 |
1997年 | 12篇 |
1996年 | 5篇 |
1995年 | 5篇 |
1994年 | 9篇 |
1993年 | 7篇 |
1992年 | 8篇 |
1991年 | 4篇 |
1990年 | 5篇 |
1989年 | 4篇 |
1988年 | 4篇 |
1987年 | 9篇 |
1986年 | 3篇 |
1985年 | 10篇 |
1984年 | 5篇 |
1983年 | 9篇 |
1982年 | 6篇 |
1981年 | 4篇 |
1980年 | 8篇 |
1979年 | 5篇 |
1978年 | 12篇 |
1977年 | 6篇 |
1976年 | 2篇 |
1975年 | 9篇 |
1974年 | 6篇 |
1971年 | 4篇 |
排序方式: 共有673条查询结果,搜索用时 15 毫秒
131.
132.
Disposition of ipriflavone (TC-80) in rats and dogs 总被引:1,自引:0,他引:1
K Yoshida T Tsukamoto H Torii T Doi I Naeshiro K Shibata I Uemura S Tanayama 《Radioisotopes》1985,34(11):618-623
Oral 14C-ipriflavone was absorbed by rats to give a maximum plasma 14C level at 1.5 h and a half-life of 5.8 h. In dogs, after po dosing, the plasma 14C peaked at 0.5 h, followed by gradual decline. The plasma of both animals contained mostly metabolites, with small amounts of unchanged ipriflavone. In rats, 14C was distributed widely in tissues, with relatively high concns. in the liver, kidney and gut. Distribution in rat thigh bone of unmetabolized ipriflavone was also demonstrated. 14C-Ipriflavone was eliminated mostly as metabolites within 48 and 72 h, respectively, in rats and dogs. Rats excreted more 14C in urine than in feces, whereas the reverse was noted in dogs. Biliary excretion and reabsorption of 14C were also obvious in both animals. 相似文献
133.
Synergistic N‐Heterocyclic Carbene/Palladium‐Catalyzed Reactions of Aldehyde Acyl Anions with either Diarylmethyl or Allylic Carbonates
下载免费PDF全文
![点击此处可从《Angewandte Chemie (International ed. in English)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Dr. Shigeo Yasuda Takuya Ishii Shunsuke Takemoto Hiroki Haruki Prof. Dr. Hirohisa Ohmiya 《Angewandte Chemie (International ed. in English)》2018,57(11):2938-2942
Benzylation and allylation of aldehyde acyl anions were enabled by the merger of a thiazolium N‐heterocyclic carbene (NHC) catalyst and a palladium/bisphosphine catalyst in a synergistic manner. Owing to the mildness of the reaction conditions, various functional groups were tolerated in the substrates. 相似文献
134.
Dr. Masahito Yoshida Dr. Koya Saito Dr. Hikaru Kato Prof. Dr. Sachiko Tsukamoto Prof. Dr. Takayuki Doi 《Angewandte Chemie (International ed. in English)》2018,57(18):5147-5150
The total synthesis of siladenoserinol A, an inhibitor of the p53–Hdm2 interaction, has been achieved. AuCl3‐catalyzed hydroalkoxylation of an alkynoate derivative smoothly and regioselectively proceeded to afford a bicycloketal in excellent yield. A glycerophosphocholine moiety was successfully introduced through the Horner–Wadsworth–Emmons reaction using an originally developed phosphonoacetate derivative. Finally, removal of the acid‐labile protecting groups, followed by regioselective sulfamate formation of the serinol moiety afforded the desired siladenoserinol A, and benzoyl and desulfamated analogues were also successfully synthesized. Biological evaluation showed that the sulfamate is essential for biological activity, and modification of the acyl group on the bicycloketal can improve the inhibitory activity against the p53–Hdm2 interaction. 相似文献
135.
136.
137.
Kusumoto T Miyamoto THiguchi R Doi S Sugimoto H Yamada H 《Chemical & pharmaceutical bulletin》2001,49(9):1207-1209
Two new and seven known compounds, including terpenoids and aromatic compounds, were isolated from the essential oil of Brazilian propolis. The structures of the new compounds were elucidated as 2,2-dimethyl-8-prenyl-6-vinylchromene (1) and 2,6-diprenyl-4-vinylphenol (2) on the basis of spectroscopic analyses. 相似文献
138.
139.
The method is based on the redox reaction between 4,4′-tetramethyldiaminothiobenzophenone (thio-Michler's ketone) and chlorine at pH 3.5; 2-methoxyethanol and Triton X-100 are used to keep the reagent in solution. The absorbance of the blue quinoidal product is measured at 640 nm. Linear calibration is obtained for 0.2?1.0 mg l?1 chlorine. The method is suitable for tap waters. 相似文献
140.
The enzymatic hydrolysis of alpha- and beta-oligo(L-aspartic acid)s by PAA hydrolase-1 and PAA hydrolase-2 (purified from Sphingomonas sp. KT-1) was performed to elucidate the mechanism of the microbial degradation by Sphingomonas sp. KT-1 of the thermally synthesized alpha,beta-poly(D,L-aspartic acid) (tPAA). GPC analysis of the hydrolyzed products of alpha- and beta-tetra(L-aspartic acid)s by PAA hydrolase-1 has showed that PAA hydrolase-1 is capable of hydrolyzing only the specific amide bonds between beta-aspartic acid units. The RP-HPLC analysis of the enzymatic hydrolysis of beta-oligo(L-aspartic acid)s (4 and 5 mers) by PAA hydrolase-1 has suggested that the enzymatic hydrolysis of beta-oligo(L-aspartic acid)s occurs via an endo-mode cleavage. In contrast, PAA hydrolase-2 hydrolyzed both alpha- and beta-oligo(L-aspartic acid)s via an exo-mode cleavage to yield L-aspartic acid as a final product. A kinetic study on the enzymatic hydrolysis of alpha-oligo(L-aspartic acid)s (3 to 7 mers) by PAA hydrolase-2 has indicated that Km values are almost independent of the number of monomer units in oligomers of 4 to 7 mers, while that Vmax values are markedly dependent on the chain length and show a maximum value at 5 mer. 相似文献